Intro to Data Analysis

Agenda

Introduction to Data Analysis
Frequency Distributions
Lab 01

📖 Readings

What’s the point?
Being a Statistician Means Never Having to Say You’re Certain

Introduction to Data Analysis

UNIT OF ANALYSIS
POPULATION
SAMPLE
N & n

DESCRIPTIVE STATISTICS
INFERENTIAL STATISTICS
TIDY DATA
VARIABLES

NOMINAL
ORDINAL
INTERVAL-RATIO
DICHOTOMOUS

Unit of Analysis

Who or what is being studied?

POPULATION

All units of analysis (people, institutions, groups, etc.) in which the researcher is interested.

SAMPLE

A subset of people (or institutions, groups, etc.) selected from a population.

Notation

N refers to population size

n refers to sample size

DESCRIPTIVE STATISTICS

Procedures that help us organize and describe data collected from a sample or population.

INFERENTIAL STATISTICS

Making underlying predictions or inferences about a population using observations and analyses from a sample.

Tidy Data

VARIABLES

Any factor, trait, or condition that can exist in differing amounts or types.

Measurement Levels

Nominal
A variable made up of categories that cannot be ordered

Ordinal
A variable made up of ranked categories, with no systematic or measurable numeric difference between the categories.

Interval-ratio (aka continuous)
A variable with categories that are ordered and expressed in the same units.

Dichotomous (aka binary)
A variable with only two categories.

Which of the following is an example of descriptive statistics?

The average age of UofT students is 21 years.
Students who study more than 10 hours a week are more likely to achieve higher grades
About 65% of U of T undergrads feels socially connected, based on a sample of 300 students.
A hypothesis test shows a significant relationship between income and education level

Which of the following is an example of a nominal level of measurement?

The type of religion a person identifies with (e.g., Christianity, Islam, Judaism)
The number of children in a household
The income of a family in dollars
A ranking of provinces by marriage rate.

Which level of measurement is used when ranking neighborhoods by crime rate (e.g., low, medium, high)?

Ordinal
Nominal
Dichotomous
Continuous

Frequency Distributions

FREQUENCY DISTRIBUTION
RELATIVE FREQUENCY DISTRIBUTION

PROPORTION
PERCENTAGE
CUMULATIVE
RATE

BAR GRAPH
HISTOGRAM
LINE GRAPH
STATISTICAL MAP

DISTRIBUTION

Shows all the possible values (or intervals) of the data and how often they occur.

FREQUENCY DISTRIBUTION

A table reporting the number of observations falling into each category of the variable.

Table 1. Attitudes about sex before marriage

Tab A
Tab B
Tab C

premarsx	n
not wrong at all	1,378
always wrong	357
wrong only sometimes	258
almost always wrong	122
Total	2,115

premarsx	n
not wrong at all	1,378
always wrong	357
wrong only sometimes	258
almost always wrong	122
Total	2,115

The number of respondents who answered this survey question.

premarsx	n
not wrong at all	1,378
always wrong	357
wrong only sometimes	258
almost always wrong	122
Total	2,115

The number of respondents who said pre-marital sex was “wrong only sometimes.”

Are women more likely than men to say premarital sex is “not wrong at all?”

Table 2. Attitudes about sex before marriage by gender

premarsx	female	male
not wrong at all	11,086	10,672
always wrong	7,116	4,159
wrong only sometimes	4,792	3,904
almost always wrong	2,388	1,499
Total	25,382	20,234

Lab 01

CODEBOOK

will add later